Synthesis and characterization of sio2chitosan supported ag au nps catalysts for catalytic reduction of malachite green a kinetic study

Abstract

newlineCatalysis play an important role in chemical industries. Most of the chemical reactions in such industries are aided by catalysts. Currently metal nanoparticles and their oxides and sulphides play a key role in Science and technology. Their size in the range 1-100nm, high surface to volume ratio and enriched active sites on the surface establish high catalytic activity and selectivity of many organic transformations. But their instability due to aggregation is a major concern. Metal nanoparticles immobilized on the surface of amine matrix, thiol matrix and 2D nanosheets were reported, but loss in activity due to many surface bonded groups that immobilise them is an another problem to be circumvented. In the present study, silica-chitosan composite was initially prepared. It was then used for immobilization of AgNPs and AuNPs separately at 3, 5, 7, 9, and 11%. They were characterized by XRD, FTIR, SEM TGA and DSC. They were examined for their catalytic activity for the degradation of malachite green in the presence of NaBH4. Malachite green (MG) has been used as an organic dye and antimicrobial agent for many years. Traditionally, it is used as a dyestuff for materials such as silk, paper, and leather in the respective industries. Improperly treated waste water from the respective industries has been constantly polluting the environment. There are several physical and chemical methods for removal of dyes, and they include membrane filtration, electrochemical technology, advance oxidation process (AOP) and adsorption process. However, most of these methods suffer from disadvantages such as high operating cost, ultraviolet (UV) irradiation at a required wavelength, long reaction time, scale-up issues and high cost. Among these methods adsorption is considered as an efficient one to remove dye pollutants due to its comparably easy operation, low cost and insensitivity to toxic substances. Recently, the natural polymers, such as chitosan and its derivatives have significantly attracted